German Patent document DE 10 2005 061 221 A1 discloses a contact element for electrically bonding an electrical conductor to a bolt, particularly a ground terminal bolt, comprising a connector plate with a central opening and an elongated conductor receptacle extending in a radial direction referred to the geometric center of the central opening. The contact element includes at least one receiving means located on the outer edge of the connector plate and formed by a tongue that is open toward the geometric center of the connector plate and projects from the plane of the connector plate, forming at least one latching element on the connector plate.
German Patent document DE 11 2008 002 974 T5 discloses a ground terminal lug for attachment to a common ground together with at least one additional second ground terminal lug with the same design, in a stacked manner, comprising an annular connecting body with a passage opening which permits the passage of the ground portion; a cable attachment portion having a bottom wall and a pair of cylinder-jacket-shaped walls standing upright from the respective bottom wall, wherein the cable attachment portion can be fixed at one end of an electrical cable by means of a plastic deformation of the pair of cylinder-jacket-shaped walls; a clamping portion having an upright portion projecting from an outer peripheral edge of the connecting body in a direction opposite to that of the cylinder-jacket-shaped walls of the cable attachment portion and a distal end portion extending inwardly from the upright portion along the connector body; and a clampable portion formed along the outer peripheral edge to lie adjacent the clamping portion in the circumferential direction of the connecting body wherein the clamping portion is capable of clamping a clampable portion of the second terminal lug by accommodating this clamped portion between the distal end portion and the connecting body, to prevent a relative displacement between superimposed ground terminal lugs in the direction of overlap of the second ground terminal lug relative to the first ground terminal lug when the first ground terminal lug is placed onto the second ground terminal lug, wherein the distal end section of the clamping section may touch the ground part if the second ground terminal lug serves as the lowest ground terminal lug and the ground part passes through the passage opening, to prevent this lowest ground terminal lug from rotating relative to the ground part.
European Patent document EP 1 746 686 B1 discloses an electrical connector element to connect an electrical conductor to a bolt, particularly a ground bolt, comprising a substantially circular connector plate with a central opening for placing the connector element onto the bolt, and a receiving area for an electrical lead elongated in a radial direction with respect to the connector plate, with at least two latch elements being provided at the connector plate externally of the central opening. When an additional connector element is mounted axially onto the connector element in a predetermined angular position with respect to the first connector element, corresponding latch elements thereof are rotationally fixed with corresponding latch elements of the first connector element. This is characterized in that the connector element has a security against rotation which is suitable for cooperating with the bolt extending through the central opening.
European Patent document EP 0 663 703 A2 shows a stackable contact part in which two tabs per contact are folded over on the outer side and point inwardly to establish the attachment to the adjacent contact part. However, the rotation lock between the contact parts is inadequate.